This invention relates generally to semiconductor power modules, more particularly, to semiconductor power modules that employ an insulated metal substrate (IMS).
The development of higher-density power electronics has made it increasingly more difficult to cool power semiconductor devices. With modern silicon-based power devices capable of dissipating up to 500 W/cm2, there is a need for improved thermal management solutions. When device temperatures are limited to 50 K increases, natural and forced air cooling schemes can only handle heat fluxes up to about one (1) W/cm2. Conventional liquid cooling plates can achieve heat fluxes on the order of twenty (20) W/cm2. Heat pipes, impingement sprays, and liquid boiling are capable of larger heat fluxes, but these techniques can lead to manufacturing difficulties and high cost.
An additional problem encountered in conventional cooling of high heat flux power devices is non-uniform temperature distribution across the heated surface. This is due to the non-uniform cooling channel structure, as well as the temperature rise of the cooling fluid as it flows through long channels parallel to the heated surface.
One promising technology for high performance thermal management is micro-channel cooling. In the 1980's, it was demonstrated as an effective means of cooling silicon integrated circuits, with designs demonstrating heat fluxes of up to 1000 W/cm2 and surface temperature rises below 100° C. Known micro-channel designs require soldering a substrate (with micro-channels fabricated in the bottom copper layer) to a metal-composite heat sink that incorporates a manifold to distribute cooling fluid to the micro-channels. These known micro-channel designs employ very complicated backside micro-channel structures and heat sinks that are extremely complicated to build and therefore very costly to manufacture.
Some power electronics packaging techniques have also incorporated milli-channel technologies in substrates and heatsinks. These milli-channel techniques generally use direct bond copper (DBC) or active metal braze (AMB) substrates to improve thermal performance in power modules.
It would be desirable to provide a power electronics packaging technique that further advances state of the art power module thermal performance while simultaneously providing superior electrical functionality characteristics than that achievable using known micro-channel, DBC and AMB power electronics packaging techniques.